Wormwood and Rotten Denmark

During the staging of his play before the king, Hamlet mutters the word “Wormwood.” Why? Irwin Matus suggests the following:

“Rarely glossed in editions of the play, wormwood is accepted as meaning only something bitter, from the taste of the plant of that name. However, the plant was also used to make a vermifuge: a syrup that expels intestinal worms. This may be the more appropriate meaning within the context of both the scene and the play, in which Hamlet seeks to expose the disease that is, so to speak, eating at Denmark—the king and the country alike.” Hamlet it pointing to the “emetic power of drama.” And Shakespeare, no doubt, expects his dramas, performed before kings, to have a similar purging effect on English politics and society. This fits neatly with the recent suggestion that Shakespeare and his fellow playwrights saw the stage as a form of preaching.